(Reuters) - Argentine President Cristina Fernandez de Kirchner struck a defiant note on Sunday in her first national address since a prosecutor announced he would continue to investigate allegations she tried to cover up a 1994 bombing, saying harsh Patagonian winters had taught her to be tough.

The accusations - first brought by a state investigator whose mysterious death last month threw the Fernandez administration into turmoil - were deemed credible on Friday by a newly-named prosecutor who said he would press on with the investigation.

In a televised speech, Kirchner did not refer to the probe. But she made it clear she would not bend under the mounting political pressure.

"Some are amazed at how I can endure all I have to endure," said Kirchner, speaking to a crowd at hospital she had just inaugurated in her adopted home province of Santa Cruz.

"I tell them it was here in Patagonia - with the wind, the cold and the snow - that I learned that I can endure anything," she said. "To live in southern Argentina you have to be tough."

Kirchner's image has taken a hit from allegations that she tried to whitewash the alleged involvement of a group of Iranians in the 1994 bombing of the AMIA Jewish community center in Buenos Aires, in which 85 people died.

She denies the accusation, which was first leveled by state prosecutor Alberto Nisman.

Nisman's body was found on Jan. 18 in his Buenos Aires apartment, a bullet in his head and a pistol by his side. The following day he had been scheduled to appear before Congress to present his case that Fernandez conspired with Iran to clear the bombing suspects in order to clinch a deal to trade grains for Iranian oil.

No conclusive evidence of either murder or suicide has surfaced. Kirchner at first speculated that Nisman killed himself, and later said rogue intelligence agents were behind his death.

The saga is expected to strengthen opposition candidates in the October presidential election, in which Kirchner is constitutionally barred from running for a third consecutive term.

(Editing by Frances Kerry)